1. Field of the Invention
The present invention relates to a reduction in noise (that is, a fluctuation component) in an image signal. In particular, the present invention relates to an image processing device configured to process an image by separating the image into a plurality of components, a program recording medium in which an image processing program is recorded, and an image acquisition apparatus that uses the image processing device.
2. Description of the Related Art
Jpn. Pat. Appln. KOKAI Publication No. 2001-157057 discloses a technique to estimate the amount of noise contained in an image and control the frequency characteristics of filtering in accordance with the estimated noise amount, thus reducing the noise contained in the image. According to the technique, when the amount of luminance noise is defined as N and a signal level converted into a density value is defined as D, the noise amount is estimated based on the function N=abcD. Here, a, b, and c are constant terms and are statically given.